Exemplary embodiments of the present disclosure relate to a brush seal, and more particularly, to a brush seal assemble used to seal a gap between a fixed body and a rotating body of a turbine.
Generally, a turbine is a power generation apparatus that converts heat energy of a fluid like gas, steam, or the like into a torque, which is mechanical energy. A turbine may include a rotor that has a plurality of buckets to rotate a shaft by the fluid and a casing that is installed to enclose a circumference of the rotor. The casing may include a plurality of diaphragms.
Herein, a gas turbine may include a compressor, a combustor, and a turbine, in which external air is sucked and compressed by a rotation of the compressor and is then delivered to the combustor. The combustor performs combustion by mixing the compressed air and fuel, and high-temperature and high-pressure gas generated from the combustor rotates the rotor of the turbine while passing through the turbine to drive a power generator.
The gas turbine and a steam turbine has a structure in which the fixed body (diaphragm) and the rotating body (rotor) relatively rotate to each other and therefore a high-temperature and high-pressure fluid is leaked through the gap between the fixed body and the rotating body. Here, the fluid leakage is one cause of reduction in energy efficiency due to a power loss. Accordingly, efforts to reduce the fluid leakage which occurs through the gap between the fixed body and the rotating body have been continuously made.
To reduce the fluid leakage, it is preferable to reduce the gap between the fixed body and the rotating body but there are restrictions in making the gap narrow.
For example, in the case in which the gap is excessively narrow, an interference occurs between the rotating body and the fixed body when the rotating body rotates about the shaft and thus vibrations occurs due to rubbing, which leads to serious damage to the turbine.
Meanwhile, since the rotating body and the fixed body are exposed to heat due to high-temperature steam introduced from a boiler, when the steam turbine is operated and the operation thereof stops, the steam turbine expands or contracts from several mm to tens of mm depending on its position. In this case, the rotating body and the fixed body expand differently due to different characteristics of materials and expand in different directions depending on a structure of the turbine. This may cause interference while the rotor and the stator are operated, and as a result, rubbing may occur.
A labyrinth seal may be used to promote sealing. A brush seal may be coupled with the labyrinth seal to reduce or eliminate the gap between the fixed body and the rotating body and promote sealing in a form which the stator and the rotor flexibly contact each other.